Plunger-operated switch with offset adjustment means

ABSTRACT

An electrical switch having a two-part body, one part carrying a spring-loaded plunger and the other part carrying an electrical contact member, and the two parts of the body having respective cylindrical surfaces which are coaxial and parallel to the axis of the plunger, but the axes of the plunger and of the said cylindrical surfaces being offset and assembly of the switch being accomplished by fitting the plunger and the contact member to the parts of the body respectively, and fitting the two parts of the body together and rotating them relatively to one another with the plunger in its inward operative position until the contact member and plunger engage the two parts of the body then being secured in such a relative position.

United States Patent Robert Leonard Gleeson Burnley, England [21] Appl. No. 886,271

[22] Filed Dec. 18, 1969 [45] Patented Nov. 2, 1971 [73] Assignee Joseph Lucas (Industries) Limited Birmingham, England [32] Priority Jan. 3, 1969 [3 3] Great Britain [72] Inventor [54] PLUNGER-OPERATED SWITCH WITH OFFSET ADJUSTMENT MEANS 2 Claims, 4 Drawing Figs.

[52] US. Cl 200/159 R, 200/166 M, 29/622 [51] Int. Cl 1101b 1/34 [50] Field of Search 200/159 R, 159 A, 166 M; 29/622, 630 C; 324/28 [5 6] References Cited UNITED STATES PATENTS 2,370,203 2/1945 Stubner ..200/l66MUX Primary Examiner- David Smith, Jr. Assistant ExaminerRobert A. Vanderhye Alt0mey-Holman & Stern ABSTRACT: An electrical switch having a two-part body, one part carrying a spring-loaded plunger and the other part carrying an electrical contact member, and the two parts of the body having respective cylindrical surfaces which are coaxial and parallel to the axis of the plunger, but the axes of the plunger and of the said cylindrical surfaces being offset and assembly of the switch being accomplished by fitting the plunger and the contact member to the parts of the body respectively, and fitting the two parts of the body together and rotating them relatively to one another with the plunger in its inward operative position until the contact member and plunger engage the two parts of the body then being secured in such a relative position.

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2g m auxz FIGA. v AT+ NEYS PLUNGER-OPERATED SWITCII WITH OFFSET ADJUSTMENT MEANS This invention relates to electrical switches of the kind comprising a body, a plunger slidably mounted in the body, and an electrical contact member which is engageable by the plunger to make an electrical connection when the plunger is in its inward position.

An object of the invention is to provide a switch of the kind specified in a convenient form.

According to the invention a switch of the kind specified is characterized in that the body has two parts, one of which carries the contact member and in the other of which the plunger is slidably mounted, the two parts of the body having interengaging cylindrical surfaces, the common axis of which is offset, but parallel to the plunger axis.

According to a method of assembling a switch of the kind specified having a two-part body, the parts carrying the plunger and the contact member respectively, and having respective coaxial cylindrical surfaces, the axis of which is offset from, but parallel to, the plungeraxis, comprising assembling the plunger and contact member to the parts of the body respectively, assembling the two parts of the body together, pressing the plunger to its inward operative position, imparting relative rotation to the two body parts about the axis of the cylindrical surfaces to bring the contact member to a position in engagement with the plunger, and finally securing the two body parts together in this position. v

The invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. I is a cross-sectional view of aswitch incorporating the present invention,

FIG. 2 is an end elevation view of one of the parts of the switch before assembly,

FIG. 3 is an end elevation view of the whole switch, and

FIG. 4 is a cross-sectional view on the line 4-4 in FIG. 1.

The switch comprises a body formed of two parts and 11.

The part 10, of the body, is, in this example, formed from metal and has a stepped bore in which is slidably mounted a spring-loaded plunger 12. The compression spring 13 of the plunger acts between a circlip l4 fitted into a groove in the plunger 12, and a washer 15 which is disposed against a shoulder within the stepped bore of the body 10.

On its external surface, the part 10 is stepped, and at one end is formed with a screw-threaded portion 16 for engagement in a component (not shown). In its midregion the external surface of the body is of hexagonal form as seen in FIGS. 2, 3 and 4, and at the end remote from the screw-threaded portion 16 there is a relatively thin-walled portion 17 which, before assembly, to the part 11, is cylindrical both internally and externally, as seen in FIG. 2.

The portion of the interior of the part 10 within the thinwalled portion 17 is cylindrical, but the axis of the cylinder is offset from the axis of the plunger 12.

The part 11, of the body, has a recessed, oblong cross section end, remote from the part 10, and to engage in the offset cylindrical portion 18 of the bore it is externally cylindrical at Within the cylindrical portion 19, and extending towards the other end, is a recess 20. Between the recesses at opposite ends of the part 11 respectively, there is a dividing wall 21, through which passes metal contact member 22. The contact member 22 is engaged over an integral portion 23 of the part 11, extending from the base of the recess at the end remote from the part 10. This part of the contact member 22 is intended to engage with a detachable connector, which is illustrated in FIG. 3, and indicated at 24, this connector being secured to the end of a cable (not shown) for conveying electrical supply to the switch.

The other end of the contact member 22 extends into the recess at the other end of the part 11, and towards the inner end of the plunger 12. The extremity of the contact member 22 is bent away from the plunger axis and the adjacent end of the lun er is rounded or bullet shaped as illustrated in FIG. 1. 0 ho d the body parts 10 and I together, the thin-walled section 17 of the part 10, is bent inwards, as shown in FIG. 4, to grip a shoulder on the outside of the part 11.

The part 11 is formed from an electrically insulating material, such as synthetic resin material.

In order to assemble the switch, the plunger, with its spring 13, is installed in the part 10 and the contact member 22 is installed in the part 11. The parts 10 and 11 are now fitted together with the cylindrical surfaces 18 and 19 interengaging as a sliding fit. The plunger 12 is moved to its inward operative position in which its inner end should engage with the contact member 22. If no such engagement takes place, the part 11 is rotated within the part 10 to a position in which the contact member 22 does engage with the plunger end. Such rotation moves the contact member 22 about an axis which is ofiset from the plunger axis.

When engagement is achieved, the parts 10 and II are secured together by defonnation of the thin-walled portion I7 of the part 10.

The outer end of the plunger 12 is intended to engage with a cam 25 on a component which is movable relatively to the switch in a direction transverse with respect to the axis of the plunger. The switch is, for example, suitable for use in operating an electrical warning light in response to predetermined changes in hydraulic brake circuits for a motor vehicle, for example, to indicate that a fault has occurred in the circuits.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. An electrical switch comprising a body, a plunger slidably mounted in the body, and an electrical contact member which is engageable by the plunger to make an electrical connection when the plunger is in its inward position, the body having first and second parts, the first part carrying the contact member and the second part slidably mounting the plunger, and interengaged cylindrical surfaces on the first and second body parts respectively the common axis of the cylindrical surfaces being offset from, but parallel to the plunger axis.

2. A switch as claimed in claim 1 in which the first and second parts have respective portions whereby they can be secured together in selected relative positions. 

1. An electrical switch comprising a body, a plunger slidably mounted in the body, and an electrical contact member which is engageable by the plunger to make an electrical connection when the plunger is in its inward position, the body having first and second parts, the first part carrying the contact member and the second part slidably mounting the plunger, and interengaged cylindrical surfaces on the first and second body parts respectively the common axis of the cylindrical surfaces being offset from, but parallel to the plunger axis.
 2. A switch as claimed in claim 1 in which the first and second parts have respective portions whereby they can be secured together in selected relative positions. 